|Publication number||US6859065 B2|
|Application number||US 10/650,465|
|Publication date||22 Feb 2005|
|Filing date||27 Aug 2003|
|Priority date||6 May 2001|
|Also published as||US6653862, US20020163358, US20040108871|
|Publication number||10650465, 650465, US 6859065 B2, US 6859065B2, US-B2-6859065, US6859065 B2, US6859065B2|
|Inventors||Brian D. Johnson, Andy L. Lee, Cameron McClintock, Giles V. Powell, Paul Leventis|
|Original Assignee||Altera Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (42), Non-Patent Citations (8), Referenced by (2), Classifications (11), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of U.S. patent application Ser. No. 10/140,911 filed on May 6, 2002, now U.S. Pat. No. 6,653,862, which claims priority to U.S. Provisional Application Ser. No. 60/289,346, filed May 6, 2001, and entitled “Use of Dangling Partial lines for Interfacing in a PLD.”
The present invention is in the field of programmable logic devices (PLD's) and, more particularly, relates to PLD's having an array of logic elements with a staggered routing architecture such that partial lines result and such partial lines that would otherwise be dangling at interfaces are driven to provide additional signal path flexibility.
Conventional programmable logic devices (PLD's) comprise an array of logic elements (LE's), and the routing architecture provides a signal path between LE's. It is desired to increase the flexibility by which signals can be driven between the PLD core and boundaries of the routing architecture.
In accordance with a broad aspect of the invention, a routing structure in a PLD is implemented in a staggered fashion. Routing lines which would otherwise be “partial” and dangling at a routing architecture boundary are driven, providing additional flexibility for routing signals to the PLD core from the boundaries.
The base signal routing architecture is defined and optimized for LE's. For example, an array of LE's is created for a particular target die size. For variants of the created LE array, as discussed in the Background, it is desired to place the IP function block within the LE array. In some embodiments, the IP function block is added as IP function blocks at some desired uniform density, although the density of IP function blocks need not be uniform. For IP function blocks added to the LE array, LE's are replaced. Thus, there is a tradeoff between LE's and the amount of IP added to the die. The array of LE's for which a particular base signal routing architecture is optimized may occupy substantially an entire target die. Alternately, a base signal routing architecture may be optimized for an array of LE's that coexists on a die with other circuitry, including other LE's.
An interface region is provided even when the IP function block is not to be bordered on all four sides by the base signal routing architecture as illustrated in the
A design consideration for the placement of a hole is the number of signal lines in and out of a hole that would result from a particular placement, primarily as a result of the extent to which the hole would border the base signal routing architecture. This can be seen with reference again to
Driving into the Mega-RAM 502 is now described. H and V routing lines in a typical embodiment connect into MRAM_LIM's 506, 606 a and 606 b (LAB input multiplexers). The MRAM_LIM 506, 606 a and 606 b is a two stage 4-way sharing multiplexer. Of the portion of the routing that terminates at the boundaries of the Mega-RAM 502, only the routing able to carry signals toward the Mega-RAM 502 feeds the MRAM_LIM's 506, 606 a and 606 b. Therefore, if the routing is unidirectional (i.e., each line can carry a signal in one direction), then routing able to carry signals away from the MRAM will not be coupled to the input interface. In another embodiment, bidirectional lines are used in addition to, or in place of, unidirectional lines.
Connectivity details of the MRAM_LIM 506, 606 a and 606 b are listed in the table of FIG. 7. Briefly,
Clock inputs 524 are taken into the Mega-RAM block 502 from the global clock network at the side of the Mega-RAM block 502 through the Mega-RAM horizontal interface 504 in (FIG. 5). The MRAM_CLOCK MUX 526 chooses one of the eight LABCLK's that are feeding through the adjacent LABs. There is one clock input to the Mega-RAM 502 per row, although the Mega-RAM 502 typically would not use every clock input available to it.
The Mega-RAM input mux (“MRIM”) is a fully populated 4-way mux-sharing mux that connects thirty LAB lines onto twenty-four I/O block inputs.
Driving out of the Mega-RAM 502 is now described. At the edge of the Mega-RAM, routing lines driving into the core do not have LAB's to drive them and are left as partial length lines. The Mega-RAM interface uses the fill-length and partial length (i.e., length four and length eight lines, in this embodiment) to connect to the core via the MRAM_DIM. The Mega-RAM interface provides similar resources as are provided for a LAB to drive onto the core routing. For example, H4 lines extending four LAB's into the core are driven, and H4 lines extending three LAB's in or less are not driven. These partial length lines are driven to Vcc. In another embodiment, the partial length lines connect to the MRAM_LIM's as described below with reference to FIG. 10.
The Mega-RAM horizontal interface can also drive signals out onto the adjacent V-channel routing. Ten partial length sneak paths (H4, H8, V16, H24) (e.g., as collectively designated by line 528) are driven directly into adjacent LAB's by ten of the twelve MegaRAM_Out signals for a “quick” path to logic.
Each MRAM driver input multiplexer (“MRAM DIM”) 612 a, 612 b supports the V-channel at the edge of the core and the half H-channel able to carry signals from the MRAM in the direction of the core. The Mega-RAM vertical interface 604 drives the full-length routing resources of two full V-channels. These drivers are dedicated to the MegaRAM_Out signals and do not support turns from other routing resources. The DIM's 612 a and 612 b associated with the V-line drivers in the Mega-RAM vertical interface 604 are used to choose between MegaRAM_Out signals. Each DIM 612 a, 612 b in the vertical interface is a 4:1 mux that can be implemented in one or more stages, and each input to the DIM is a MegaRAM_Out signal. The connection pattern from the MegaRAM_Out signals to the DIM 612 a, 612 b is typically spread equally between the two V-channels.
The number of MegaRAM_Out signal connections per DIM for each of the Mega_RAM Horizontal Interface (
It is noted that, typically, not all IP function blocks need be incorporated into an LE array using the hole concept. For example, the IP function block may be of two types—small and large. In general, the terms small and large as used here can be thought of as indicating size. One actual design consideration, however, in determining whether to consider particular IP function block as small or large is a consideration of how much disruption to the timing of signal routing is to be tolerated. For example, in accordance with one embodiment, a small block is an IP function block whose layout can be drawn at a width on the order of an LE width. In accordance with this embodiment, the width of small blocks may be wider than an LE so long as the timing of signal routing over the block does not get significantly larger than for routing over an LE. For example, in one 0.13 μm architecture, it has been deemed that the timing of the signal routing over a block of roughly 5 LE widths does not get significantly larger than for routing over an LE. Typically, additional inputs and/or outputs may be added that exceed the width of an LE, so long as the base signal routing architecture across the IP function block is maintained with the LE's surrounding the small block. Another consideration for determining whether an IP function block is large (implemented using the hole concept) or small is the size of the IP function block relative to the overhead associated with employing an interface region. In one embodiment, small blocks include MEAB's (medium sized embedded array blocks), SEAB's (small sized embedded array blocks) and a DSP block. By contrast, large blocks are IP function blocks that typically have dimensions much larger than that of an LE. Extending the base signal routing architecture across these blocks without modification would cause routing over these blocks to be significantly larger than routing over an LE, forming a boundary in the PLD timing model. Such large blocks may be inserted into the LE array as holes in the base signal routing architecture, as described above. In some sense, what occurs at the boundary between the base signal routing architecture and a hole is similar to the base signal routing architecture ending at the edge of an LE array.
In some embodiments, shown with reference to
Signal selection muxes may be used in front of the drivers to add routing flexibility. The connection may include a programmable connection such as static random-access memory, dynamic random-access memory, electrically erasable programmable read-only memory, flash, fuse, and antifuse programmable connections. The connection could also be implemented through mask programming during the fabrication of the device. As described above, the routing may also be implemented with segmented bidirectional lines.
The partial lines 1002 driving out of the PLD core 1001 feed an input selection mux 1012 to drive into the logic block 1004. These partial lines 1002 impose a smaller load on the drivers 1014 than do full lines 1016, and having a small load makes the partial line 1002 a faster path into the PLD core 1001. If area is a concern, drivers 1018 for partial lines 1002 may be smaller than drivers 1020 for full lines 1016, and still not be at a speed disadvantage due to the smaller load.
Furthermore, by driving even the partial lines 1002, additional routing flexibility is provided for signals from the PLD core 1001 to the PLD boundaries. Allowing the partial lines 1002 headed out of the PLD 1001 to drive into an IP function block 1004 increases the routability from the PLD core 1001 to the logic block 1004. In addition, the additional drivers 1018 may be used to provide the core 1001 access to more signals, or the signals may be used to provide more paths into the PLD core 1001 for a given signal. Thus, quite simply, lines that would have otherwise been unused are utilized to provide needed access to the PLD core 1001.
While the present invention has been particularly described with respect to the illustrated embodiments, it will be appreciated that various alterations, modifications and adaptations may be based on the present disclosure, and are intended to be within the scope of the present invention. While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the present invention is not limited to the disclosed embodiment but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the claims. For example, the techniques described herein may be applied to other types of fixed blocks or routing structures.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4870302||19 Feb 1988||26 Sep 1989||Xilinx, Inc.||Configurable electrical circuit having configurable logic elements and configurable interconnects|
|US4871930||5 May 1988||3 Oct 1989||Altera Corporation||Programmable logic device with array blocks connected via programmable interconnect|
|US5121006||22 Apr 1991||9 Jun 1992||Altera Corporation||Registered logic macrocell with product term allocation and adjacent product term stealing|
|US5241224||25 Apr 1991||31 Aug 1993||Altera Corporation||High-density erasable programmable logic device architecture using multiplexer interconnections|
|US5243238||17 Mar 1990||7 Sep 1993||Algotronix Limited||Configurable cellular array|
|US5260611||8 May 1992||9 Nov 1993||Altera Corporation||Programmable logic array having local and long distance conductors|
|US5359536||3 Mar 1993||25 Oct 1994||Advanced Micro Devices, Inc.||Programmable gate array with improved interconnect structure, input/output structure and configurable logic block|
|US5455525||6 Dec 1993||3 Oct 1995||Intelligent Logic Systems, Inc.||Hierarchically-structured programmable logic array and system for interconnecting logic elements in the logic array|
|US5485103||15 Dec 1994||16 Jan 1996||Altera Corporation||Programmable logic array with local and global conductors|
|US5537057||14 Feb 1995||16 Jul 1996||Altera Corporation||Programmable logic array device with grouped logic regions and three types of conductors|
|US5541530||17 May 1995||30 Jul 1996||Altera Corporation||Programmable logic array integrated circuits with blocks of logic regions grouped into super-blocks|
|US5550782||18 May 1994||27 Aug 1996||Altera Corporation||Programmable logic array integrated circuits|
|US5557217||31 Oct 1994||17 Sep 1996||Altera Corporation||High-density erasable programmable logic device architecture using multiplexer interconnections|
|US5581199||4 Jan 1995||3 Dec 1996||Xilinx, Inc.||Interconnect architecture for field programmable gate array using variable length conductors|
|US5592106||17 May 1995||7 Jan 1997||Altera Corporation||Programmable logic array integrated circuits with interconnection conductors of overlapping extent|
|US5656950 *||26 Oct 1995||12 Aug 1997||Xilinx, Inc.||Interconnect lines including tri-directional buffer circuits|
|US5682107||19 Mar 1996||28 Oct 1997||Xilinx, Inc.||FPGA architecture with repeatable tiles including routing matrices and logic matrices|
|US5689195||17 May 1995||18 Nov 1997||Altera Corporation||Programmable logic array integrated circuit devices|
|US5701091||6 Jun 1995||23 Dec 1997||Xilinx, Inc.||Routing resources for hierarchical FPGA|
|US5705939||15 Oct 1996||6 Jan 1998||Altera Corporation||Programmable logic array integrated circuits with segmented, selectively connectable, long interconnection conductors|
|US5760604||3 Jun 1996||2 Jun 1998||Xilinx, Inc.||Interconnect architecture for field programmable gate array|
|US5847579||20 Mar 1997||8 Dec 1998||Xilinx, Inc.||Programmable logic array with improved interconnect structure|
|US5880598||10 Jan 1997||9 Mar 1999||Xilinx, Inc.||Tile-based modular routing resources for high density programmable logic device|
|US5900743 *||16 Sep 1997||4 May 1999||Altera Corporation||Programmable logic array devices with interconnect lines of various lengths|
|US5903165||2 Jun 1994||11 May 1999||Motorola, Inc.||Programmable logic array with a hierarchical routing resource|
|US5907248||9 Feb 1998||25 May 1999||Xilinx, Inc.||FPGA interconnect structure with high-speed high fanout capability|
|US5909126||28 Jun 1996||1 Jun 1999||Altera Corporation||Programmable logic array integrated circuit devices with interleaved logic array blocks|
|US5914616||26 Feb 1997||22 Jun 1999||Xilinx, Inc.||FPGA repeatable interconnect structure with hierarchical interconnect lines|
|US5942913||20 Mar 1997||24 Aug 1999||Xilinx, Inc.||FPGA repeatable interconnect structure with bidirectional and unidirectional interconnect lines|
|US5977793||13 May 1997||2 Nov 1999||Altera Corporation||Programmable logic device with hierarchical interconnection resources|
|US6002268||26 Nov 1997||14 Dec 1999||Dynachip Corporation||FPGA with conductors segmented by active repeaters|
|US6084429||24 Apr 1998||4 Jul 2000||Xilinx, Inc.||PLD having a window pane architecture with segmented and staggered interconnect wiring between logic block arrays|
|US6107824||28 May 1998||22 Aug 2000||Altera Corporation||Circuitry and methods for internal interconnection of programmable logic devices|
|US6204690||18 May 2000||20 Mar 2001||Xilinx, Inc.||FPGA architecture with offset interconnect lines|
|US6218859||26 May 1999||17 Apr 2001||Altera Corporation||Programmable logic device having quadrant layout|
|US6278291||21 Jul 2000||21 Aug 2001||Altera Corporation||Programmable logic array devices with interconnect lines of various lengths|
|US6289412||12 Mar 1999||11 Sep 2001||Legend Design Technology, Inc.||Layout synopsizing process for efficient layout parasitic extraction and circuit simulation in post-layout verification|
|US6292018||29 Mar 1996||18 Sep 2001||Xilinx, Inc.||Configurable cellular array|
|US6300794||20 Jan 2000||9 Oct 2001||Altera Corporation||Programmable logic device with hierarchical interconnection resources|
|US6484291||27 Apr 2000||19 Nov 2002||Oki Electric Industry Co., Ltd.||Library for storing pattern shape of connecting terminal and semiconductor circuit designed with different design rules|
|US6605962||25 Jan 2002||12 Aug 2003||Altera Corporation||PLD architecture for flexible placement of IP function blocks|
|US20010033188||13 Mar 2001||25 Oct 2001||Edward Aung||Clock data recovery circuitry associated with programmable logic device circuitry|
|1||Altera Corporation (Jun. 1996). "Max 7000: Programmable logic device family" Data Book, A-DB-0696-01, version 4, pp. 193-261.|
|2||Altera Corporation (Oct. 2001). Excalibur "Description of the The Floor plan", pp. 1-1 through 1-10.|
|3||Betz, V. et al., (1999). "Detailed Routing Architecture," Chapter 7 In Architecture and CAD for Deep-Submicron FPGAs, Kluwer Academic, Boston, pp. 151-190.|
|4||Betz, V. et al., eds. (1999) "Background and Prevoius Work," Chapter 2 In Architecture and CAD for Deep-Submicron FPGAs, Kluwer Academic, Boston pp. 12-18.|
|5||Betz, V. et al., eds. (1999). "Global Routing Architecture," Chapter 5 In Architecture and CAD for Deep-Submicron FPGAs, Kluwer Academic, Boston, pp. 105-126.|
|6||Betz, V. et al., eds. (1999). "Routing Tools and Routing Architecture Generation," Chapter 4 In Architecture and CAD for Deep-Submicron FPGAs, Kluwer Academic, Boston, pp. 63-95.|
|7||Xilinx. (Nov.2000). "Programmable Logic: News and Views, a monthly report on developments in the PLD/FPGA industry" Electronic Trend Publications, Inc., IX(11):14-15. (Includes Table of Contents).|
|8||Xilinx. (Oct. 2000) "Putting It All the Together, The Vitrex-II Series Platform FPGA: World fastest logic routing" Xilinx brochure, p. 83.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8732646 *||20 Mar 2013||20 May 2014||Altera Corporation||PLD architecture for flexible placement of IP function blocks|
|US9094014||2 Apr 2014||28 Jul 2015||Altera Corporation||PLD architecture for flexible placement of IP function blocks|
|U.S. Classification||326/41, 326/47, 716/128, 716/117|
|Cooperative Classification||H03K19/17732, H03K19/17748, H03K19/17736|
|European Classification||H03K19/177D4, H03K19/177F, H03K19/177H|
|17 Jul 2008||FPAY||Fee payment|
Year of fee payment: 4
|25 Jul 2012||FPAY||Fee payment|
Year of fee payment: 8